Drilling wells to recover oil and gas typically requires introducing a drilling fluid into the well bore and recirculating the drilling fluid up and out of the well bore to lubricate the drilling components, such as the drill string and drill bit, and to maintain the integrity of the well bore during operation of the drill. As the drilling fluid is recirculated up the well bore, the fluid acts as a sealant to keep the walls of the well bore in place, which, among other things, allows the drill pipe to be raised or lowered without obstruction and facilitates removal of drilled material from the well bore.
Lost circulation materials, such as cottonseed hulls, cedar fiber, paper, cottonseed burrs, sawdust, cellophane, calcium carbonate and phenolic plastic, are used as additives in the drilling fluid to fill fissures, porous or fractured formations, or other undesirable subterranean characteristics existing or formed in the side walls of the well bore. Filling the voids in the well bore wall with lost circulation material helps to prevent the recirculating drilling fluid from filling the voids, losing drilling fluid, and ultimately preventing efficient circulation of the fluid and removal of debris from the well, or even complete cessation of the drilling process.
Transporting or delivering lost circulation materials in bulk from a source to the drilling fluid for mixing with the fluid prior to pumping the fluid into the well can be difficult. A known method includes manually unloading large sacks of hulls, e.g., 100-pound sacks, from a transportation vehicle and manually pouring the contents of the sacks into a hopper on top of a mud pit or drilling well for mixing with the drilling fluid. This method, however, can be undesirably inefficient and labor intensive.
In another known method, the lost circulation materials are drawn from a source by a pump, pumped through the pump, discharged out of the pump and through an exhaust, and introduced into the drilling fluid. One known drawback with this method is that the lost circulation materials being pumped through the pump can damage, or otherwise disrupt the performance of, the pump by contacting the pump's moving parts or lodging in portions of the pump resulting in congestion and backup of lost circulation material flow.
Therefore, it would be advantageous to develop methods and systems for delivering lost circulation material, including cottonseed hulls that overcome the drawbacks of known systems.